<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        let obj = {
            username: 'zhangsan',
            password: '123'
        };

        let json = JSON.stringify(obj)
        let json = JSON.stringify(obj)

        obj.password = ''
        delete obj.password

        let arr = [0, 1]
        arr.




            Bom
        location
        host: arr
        herf: arr
        protocol: arr
        location.host
        location.herf
        location.protocol
        history.back
        history.forward

        DOM
        HTML
        innerHTML
        CSS
        style

        JSON


    </script>

</body>

</html>
copyWithin，entries,flat,reduce,lastIndexOf,values,toLocaleString